I've got NPP and what I really need is the ability to force the valves closed while in track mode. I've had issues passing sound control (90 db) at one of my local race tracks, Laguna Seca. I read the NPP fuse pull trick thread but that forces them to open all the time.

 

I second this request, for me it's not a track, it's that I'll get arrested driving around in anything but touring mode/weather/eco modes..

 

Glad to see there are some real tech guys on this forum. I'll save these names for any problems I have.

 

There is no adjustment on the tips/axleback? Mine are all even but tilted about 1/4 inch...one side lower than the other.

 

See Brentano post of 11-29-14 in Tech/Perf. forum. Great solution to your problem.

 

When power was applied to the valve, did it change position instantly, like a solenoid, or was it a gradual change, such as with a zone valve control used in home heating systems?
If it moves slowly, possibly the PWM is not a requirement for the control of the position as in stepper motors, but instead is to limit the power draw to the valve, if it only needs a periodic maintenance pulse to keep it closed against the opening spring. The valve may not be rated for continuous application of power, so the duty cycle of the PWM may be set up to simply give it enough to keep it in position.
If that's the case, a simple fixed PWM may serve the purpose.
The problem with it not moving at all when installed in the car is another issue though. That should be easy enough to fix though, it's either missing the 12V or the ground return.

 

I love it.

 

I really want a dial or switch to let me make my exhaust quieter, like cole above, I really don't want to have to lift at the sound booth or run in Touring mode.

Did anyone figure out if sending a simple PWM signal to the valve was all that is needed? Is anyone interested in working on this?

 

Been working on this, as have several people. Best we have for now is a switch that allows for 41 to be open or closed. That's the easiest way to open and close the valves while driving - just have to make sure Engine Sound Management is on. Then it's just a flick of the switch, and going into Touring mode.

There's no real reason to go all the way back to those valves to inject a PWM when you can just cut the 12V signal. The 12V cut will not cause any codes, while injecting a PWM signal could have odd effects - we just don't know.

The switch is incredibly easy if you've wired anything from the cabin into the engine compartment / fuse box.

 

The boat I'm stuck in is that I need mine to be quieter, not louder. I wish the car let you pick between auto, off and on instead of just auto and off. I want track mode for the awesome traction control modes, steering and suspension... but I need my exhaust to be quiet for damn Laguna Seca.

My thought was a switch that flipped between a pwm signal generator and the car's computer. That way, I could let the car control the noise most of the time... but when needed, I can take over and tune the loudness.

Has anyone hooked up a hobby servo pwm signal generator to it and seen what happens? Or maybe the device from Amazon linked way back? I was hoping someone had already figured it out, personally. Maybe sponsor someone to figure it out by purchasing them an extra valve?

 

Technically, an offboard PWM hobby circuit should close those up by supplying power. You'd just wire a switch to it and feed from a 12v circuit. Every wireless one I tried using failed horribly - too much interference in the system.

I hate the requirements for Laguna Seca - I don't think the stock Z06 even meets the new noise rules, which is stupid. But I digress...

Ideally, you'd want to decouple it from the system entirely to not have any feedback into the CCM. You'd lose the ESM control, but would essentially have your own M2W setup.

As far as I know, nobody's done this, but the idea is fairly sound - I believe the pinout is available here (if not in this thread, in the other) for the valve. Removing the control of the valves also (surprisingly) doesn't fire a code, so you're good there.

 

Yeah, I saw the circuit diagram. I'll add this to my list of things to do in the future! At least the idea isn't crazy. My *stock* Z51 blew sound at Leguna Seca. Now with headers, it is even loader. But Touring mode is still pretty quiet!

 

I was wondering if you were running stock class or if you had mods.

Keep in mind that if you really just get fed up with it, you could just have a manual butterfly (blocker plate) installed right in front of or behind the valve. All depends on how often you race and how complex (or lack thereof) you want to get.

Not very elegant, but some people may actually prefer that to additional wiring (even though in this case, it's not too bad of a job, assuming the PWM works well enough - and supplies a constant feed).

 

Side note - this may be something that the lot of you wanting this 'track quiet' option should approach GM (even here on the boards) directly about.

GM is fairly serious about making the Z06 a true competitor in the hands of the everyday driver, and sound ruling on tracks like Laguna really prohibit much of anything. I've not compared the dBa rules to the Z06 stated numbers, but I can say that the dBa and dBc measurements that I've actually taken from the Z06 exceed the factory stated numbers by a large margin.

May not do a damned thing, but it's something to consider. A lot of these service campaigns have actually started from one or two people escalating their concerns to a regional service manager.

Just a thought while we all figure something else out. Seems like an oversight.

 

The first part of this is done with regard to having a manual override switch. The second part of closing the valves electronically in Sport and Track will require something similar to what the 'non-NPP to NPP' guys are wanting - taking the CCM out of the mix, and simply reverting back to an on/off switch for the NPP - no more computer control in the mix.

If anyone looking to do this (or any forum vendor/sponsor) would care to send me a valve, PM me, and I will start working on a solution for the PWM circuit (and I will cover the purchasing any additional test items, etc). You will get the valve back at the end of testing, which (being honest here) could take a bit.

 

Good news for most everyone here - the work I've been doing has finally yielded successful results. Only required a few thousand dollars in hardware and testing supplies to make this a reality. That part kind of hurt - was hoping to start some sort of crowdfunding to ease that blow, but I'm not sure that's kosher with regard to forum rules.

A member here (not sure if he'd like me to mention his username) was kind enough to split the cost of the NPP exhaust with me, as I needed one to test with outside of the vehicle. That will be sold after the project, so someone will have a chance to pick up a nearly-new system for a good price.

I will be posting a large thread of findings, etc. in the interest of the community and future development. I'd love to be able to sell the idea to a vendor here to recoup some of my expenses, but that generally doesn't run parallel to my open-source beliefs. I also fear that GM may be litigious about it, so like always, I am simply sharing the results obtained from my personally-owned vehicle and parts.

The replication of the necessary signals is something that can not be duplicated by anything available through Amazon or normal channels - I've purchased nearly a dozen devices in the hopes of finding one that will output the exact signal needed, but it's a little screwy. So, while I anticipate people saying 'it's just a simple $10 fix', it's actually not. In fact, it's taken two different waveform function generators (at $300 a pop) and a new, beefy digital oscilloscope to properly output and filter the I/O from pins 2 and 3.

I have a few devices en route from Hong Kong that are more tailored to exactly what we need to do this. If that doesn't pan out, I'll design a circuit board from scratch and put the schematics up.

This will be a solution for both camps here - those who wish to retrofit NPP on a non-NPP vehicle, and those with factory-NPP who wish to have a force-closed option for the track. For the latter, I have also devised a circuit to keep CCM control as a three-position switched option.

Anyway... just wanted to update, as I've not posted in about a week - literally been spending every possible minute on this. Have around 50 hours in it after counting yesterday.

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Aren't you really talking about a "forced open" position for the track?

 

No, forced closed for tracks with low sound limits. In track mode, I blew a 104db at Laguna Seca on the stock exhaust. It is much quieter in Touring mode, but you don't get any of the awesome steering feel, stiff suspension and most importantly the 5 track modes. Or you lift like a big baby at the sound check point.

But really, it'll be a force open, closed *or* let the car choose switch. The best of all worlds, gives everyone what they need!

 

FWIW, for those who may not know, you can override the steering setting to be what you want in the Driving Mode settings (vs. tied to driving mode) just like Engine Sound Management. The Stealth mode (introduced in 2015) helps under 4k RPM so you have to lift less. Unfortunately the mag ride is always tied to driving mode dial (pre-launch removal from user menu).

Ultimately, Theta's work here is the only -true- way to get what most of us expected the NPP controls to do... Too bad it was this hard (and costly for Theta!).

 

Jesus, yeah seriously. They really should have let us edit our modes to exactly what we wanted. Let us tune the steering, suspension and exhaust via settings. I've never seen steering mode settings in the menus, is this a 2014 vs. 2015 thing? Automatic vs. manual? Or maybe I'm just totally blind or the settings menus are goofy?